US Open Cup: Round of 16 set for kick with 12 MLS clubs in action | Matchday Preview

An even dozen Major League Soccer sides survived the lower-tier gauntlet to make the US Open Cup Round of 16, which takes place on Wednesday night.

MLSsoccer.com will have full coverage of the matches, including a live chat with updates and reports from the matches. In the meantime, here's a roundup preview to get you prepared for what could be a wild night of action.

After squeezing by the Richmond Kickers in penalty kicks following 120 minutes of scoreless soccer, United will face a familiar Open Cup foe Wednesday in the Union. Philadelphia eliminated D.C. from the tournament last year with a 2-1 victory in overtime and the clubs will meet again this year at the SoccerPlex in Boyds, Md.

Philly have seven points in their last five MLS matches, while United remain winless since March 9. D.C.'s newly acquired defender Alain Rochat won't be available for selection against Philadelphia, but would be eligible as soon as August 7 should United advance.

For the third straight year, Union manager John Hackworth expects the game to be a heated affair between the two bitter rivals.

“I would be surprised if we finish [Wednesday night] 11 vs. 11,” he said.

Not only have the last two Open Cup matchups between Philly and D.C. been extremely testy with nine total yellow cards and four combined ejections, they’ve been equally wild. D.C. United won the 2011 contest in penalty kicks, before the Union got their revenge with an overtime win last year en route to a trip to the USOC semifinals.

So what is it about the Maryland SoccerPlex that leads to such craziness?

“For whatever reason, with the fans right there close, it’s been an emotionally charged setting,” Hackworth said. “Once that happens twice, you kind of start to expect it.” — Nick Cammarotaand Dave Zeitlin

With José Luis "El Chelís" Sánchez Solá gone, Chivas USA will continue their adjustment to a four-man backline under interim head coach Sasha van der Most in their trip to face the Carolina RailHawks. Chelís' final match at the helm came May 28 in the Goats' 2-1 come-from-behind victory against the LA Blues in the third round, and Chivas USA are heading in a different direction tactically following the switch.

“We’ve done a lot of tactical work – how to defend and how to attack,” midfielder Jorge Villafaña said in a statement. "I think we are working to form a new base and remake the team."

New head coach José Luis "Guero" Real will be introduced in a press conference Thursday and the Rojiblancos would like to welcome him with a victory. — Blair Angulo

New England coach Jay Heaps will likely lean on his reserves against New York with a visit to Vancouver looming on Saturday. Kalifa Cissé, Andy Dorman, Ryan Guy and Matt Reis could all feature from the start as the Revs attempt to secure a place in the final eight at sold-out Soldiers Field Soccer Stadium in Boston. Heaps can also turn to Gabe Latigue and Tyler Polak if he so chooses after the Revs recalled the duo from USL PRO side Rochester ahead of this match.

"The great thing about the team right now is that there is a lot of depth," Guy said. "Every week, it's a competition to see who is going to be on the pitch, who is starting, who is coming on. This is just another opportunity. I think Jay has been very good about honoring guys who show well in competition. That's what I'm looking to do."

The last time the New York Red Bulls took to the field, they suffered a defeat at home to the Vancouver Whitecaps that left a sour taste in their mouths.

The Red Bulls, meanwhile, have a chance to bounce back a loss to Vancouver but will need to beat a familiar foe that is currently on a roll. New York will be without the likes of Thierry Henry and Tim Cahill, but they should still field a talented side that includes Ryan Meara, Juninho, Heath Pearce and Péguy Luyindula.

This match will also give midfielder Lloyd Sam another opportunity to make a case for why he should be starting and Meara another chance to play, it could also mark Revolution forward Juan Agudelo’s first clash against his former club. Agudelo has not suited up against the Red Bulls since being traded by his hometown team last summer and how New York fare against him, should he play, will be one of the key storylines. — Kyle McCarthy and Franco Panizo

Wednesday night's match could see Sporting KC forward Teal Bunbury take the pitch for the first time since an ACL tear ended his 2012 season late last August. Beyond that, both sides' depth will be tested – but for different reasons – when Sporting host their USL PRO affiliate.

Six players are off on international duty for the hosts, and right back Chance Myers will miss the match with a nagging groin strain he picked up in Sporting's 2-0 win over the Des Moines Menace in the third round two weeks ago. Kansas City's other regular right back, Mechack Jerome, is with Haiti's national team. That could leave Homegrown player Kevin Ellis to make his competitive debut in his third season with Sporting.

A few games ago, midfielder Alex was an afterthought. Now he's looking more and more like a fixture in the Chicago Fire starting lineup. The Brazilian made his first start of the year in a 2-0 win over the Charlotte Eagles two weeks ago in the Fire's first Open Cup game, and he'll probably start his fourth straight game on Wednesday against Columbus.

Captain Logan Pause should make a return to the starting lineup after hurting his groin against the Eagles. He could be instrumental in shutting down Federico Higuaín, as he was the last time the two teams played, a 1-0 Fire win in April.

But Fire coach Frank Klopas knows stopping Higuaín and forward Dominic Oduro will take more than strong plays from Pause.

“They're dangerous players,” Klopas said. “I think it's a whole-team effort. We've got to make sure we're focused for 90 minutes. We know about Dom's pace, and Higuaín, he's a difference-maker and an excellent player. He's someone that you've got to have your eyes on for 90 minutes. It's not easy to stop these guys.”

For the Crew, standout forward Higuaín is expected to lead a lineup with many of the same players who started last week's 3-0 league loss at Philadelphia when the Columbus travel to Chicago. Center midfielder Danny O'Rourke, coming back from injury, may start and Konrad Warzycha might see action in the middle. Bernardo Añor is in the mix for the left flank and former Fire striker Oduro is a candidate at forward.

Coach Robert Warzycha would not say if Andy Gruenebaum or backup Matt Lampson would be in goal. — Craig Merz and Anthony Zilis

The Dynamo will be looking for a measure of payback when they face their Texas rivals on Wednesday night. Houston fell to a heartbreaking 3-2 loss in Frisco in March on a controversial stoppage-time Kenny Cooper goal in league play. A notable inclusion Wednesday will be the return to competitive play of Omar Cummings, who head coach Dominic Kinnear said would see time after appearing in a Reserve League match last weekend. Coming off a bye week and with another ahead, Kinnear could opt for a stronger-than-normal lineup with more options at his disposal.

In the hosts' corner, FCD head coach Schellas Hyndman confirmed after practice on Tuesday that Cooper, who has been recovering from a concussion, has been cleared by doctors to play in Wednesday's game. Hyndman plans to field a very competitive lineup, but says that depending on how the match goes, he’d like to give quality minutes to some players that haven’t seen much first-team game time, including Homegrown forwards Bradlee Baladez and Jonathan Top, as well as Homegrown center back London Woodberry and backup center back Stephen Keel. — Darrell Lovell and Matt Barbour

When Jason Kreis fills out his lineup for Wednesday's game against the Battery, there are two positions where he can’t go wrong — the forwards. RSL’s all-time leading scorer Álvaro Saborío is away with the Costa Rican national team, but unlike past years where that may have meant a long 90 minutes, the cupboard is hardly bare. The four remaining forwards, Joao Plata, Robbie Findley, Devon Sandoval and the reigning MLS Player of the Week Olmes García are all in terrific form right now. Not only are they in great form, they are all putting in the extra work expected of them from Kreis for the team to be successful.

With that approach, RSL are expected to put out a lineup heavy with first XI players against their third-division visitors. As for now, the early lineup distributed to the media — something that can clearly be changed before gametime — has Sandoval and García starting up top. — Michael Black

This match comes at a tricky time for the Timbers, who are entering a crucial stretch of three Western Conference games over the course of the next two weeks. And it appears that Portland will field a starting XI consisting of younger players and part-time starters against Tampa Bay, one four lower-division sides still alive in the tournament. According to captain Will Johnson, Tampa Bay are a much better team than the Wilmington Hammerheads, the side the Timbers throttled 5-1 in the third round.

“You have to be very, very wary and you’ve got to have your guard up and prove why we’re the MLS and those guys are on an NASL team,” Johnson said. “But yeah, if you don’t have your guard up, they’ve got more than enough to beat you.” — Dan Itel